Door latch mechanism

ABSTRACT

A door latch having a rotary latch bolt journalled in a casing secured to a door for engagement with a fixed strike on a door frame. The latch bolt is yieldingly biased toward an unlatched position relative to the strike, and is formed to provide a ratchet that is engaged by a cooperating pawl on a latch actuator to be held in a latched position in engagement with the strike. A locking device, mounted in the casing, is operatively connected to the actuator by a link, and is operative to restrain movement of the actuator in a direction to unlatch or release the rotary latch bolt for movement to its strike released position.

United States Patent [1 1 Colombo et al.

[111 3,746,381 [4 1 July 17, 1973 DOOR LATCH MECHANISM [73] Assignee: Ideal Security Hardware Corporation, St. Paul, Minn.

[22] Filed: Sept. 23, 197] [2]] App]. No.: 182,960

[52] US. Cl. 292/216 [51] Int. Cl. E05c 3/24 [58] Field of Search 292/198, 210, 221, 9 292/229, 216

[56] I References Cited UNITED STATES PATENTS 3,439,948 4/1969 Smith... 292/21q 7/1925 Watts 292/216 3,423,l l8 i/l969 Waldo 292/229 Primary Examiner-Richard E. Moore Attorney--Arthur E. Ringsrud [5 7] ABSTRACT A door latch having a rotary latch bolt journalled in a casing secured to a door for engagement with a fixed strike on a door frame. The latch bolt is yieldingly biased toward an unlatched position relative to the strike, and is formed to provide a ratchet that is engaged by a cooperating pawl on a latch actuator to be held in a latched position in engagement with the strike. A locking device,mounted in the casing, is operatively connected to the actuator by a link, and is operative to restrain movement of the actuator in a direction to unlatch or release the rotary latch bolt for movement to its strike released position.

4 Claims, 13 Drawing Figures ,PATENIED JUL 1 1 I975 SHEU 2 BF 2.

imam/[rs DOOR LATCH MECHANISM BACKGROUND OF THE INVENTION This invention is .in the nature of an improvement over the door latch disclosed in U. S. Letters Patent No, 3,423,118, issued to Russell W. Waldo, assignor to the assignee of this invention. The structure disclosed in the patent includes a spring pressed latch bolt driver that is slidably mounted in a casing and engages a tongue on the latch bolt to rotate the same to a released position. A pawl is journalled in the casing, having engagement with a ratchet tooth on the latch bolt, the pawl being movable by engagement with an actuator in the nature of a handle, to permit the latch bolt to move. One problem occurring with the use of a more-or-less exposed sliding member is that the same is subject to dust or other foreign matter which might adhere thereto and interfere with free movement of the sliding member. Further, spring pressure of the sliding member spring applied against the rotary lock renders the same somewhat difficult to rotate, particularly with the use of a key applied from the exterior side of the door.

- SUMMARY OF THE INVENTION An important object of this invention is the provision of a rotary latch having an extremely simple latch actuating mechanism.

Another object of this invention is the provision of a rotary latch mechanism having a locking device in which the locking effort can be overcome by the latch actuator mechanism from one side of the door but not from the opposite side of the door.

Another object of this invention is the provision of a rotary latch having mechanism which prevents a door from being latched when the latch is locked in a latched position while the door is open.

To the above ends, we provide a rotary latch including a casing adapted to be secured to one side, such as the inside, of a door hinged in a door frame; a rotary latch bolt journalled in the frame; a stationary strike element adapted to be mounted on the door frame for latching engagement with the latch bolt; a handleequipped latch actuator pivotally mounted in the easing and having a pawl engageable with ratchet teeth on the latch bolt; a push-plate element journalled in the casing for engagement with the actuatorand adapted to be connected toa second latch actuating member on the opposite, or outer, side of the door; and a lock mechanism for restraining the handle-equipped latch actuator against movement in a direction to release the rotary latch bolt from latching engagement with the strike element. The push-plate element is so arranged that pressure thereaginst from the opposite side of the DESCRIPTIONOF THE DRAWINGS FIG. 1 is a fragmentary view in side elevation of a door and door frame member with the latch mechanism of this invention mounted thereon;

FIG. 2 is a fragmentary view in edge elevation of the FIG. 4 is an enlarged fragmentary section taken sub stantially on the line 4-4 of FIG. 1;

FIG. 5 is a view corresponding to FIG. 4 but showing a different position of some of the parts;

FIG. 6 is a fragmentary view in side elevation, as seen from the line 6--6 of FIG. 3, some parts being broken away;

FIG. 7 is a view corresponding to FIG. 6, but showing a different position of some of the parts;

FIGS. 8 and 9 are fragmentary sections taken on the lines 88 and 9-9 respectively of FIG. 3;

FIG. 10 is a fragmentary detail in section taken on the line l--l0 of FIG. 4;

FIG. 11 is a view in perspective of a push-plate element of this invention;

FIG. 12 is a view in perspective of a rigid link; and

FIG; 13 is a fragmentary view in perspective of the latch actuator of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, the free edge portion of a door, such as a screen or storm door, is indicatedat l, the door being mounted in a door frame 2 for swinging moveassumed that the door 1 swings outwardly with respect to the door frame 2 in the usual manner.

Our present door latch involves a casing molded or cast from metal or other suitable material to form an inner or base portion 6, having a peripheral flange 7 that engages the inner surface 4 of the door l,'opposite side walls 8 and 9 that project laterally outwardly from the base portion 6, and an outer end wall portion connecting the outer ends of the side walls 8 and 9 and formed to provide an inturned lip or flange 11. As shown, the casing 5 is adapted to be rigidly secured to the door 1 by mounting screws or the like 12. As shown in FIG. 2, the screws 12 extend through transverse openings 13 in the door 1, and are screw-threadedly received in screw-threaded bosses l4 projecting inwardly from an outer latch handle 15 preferably of the type disclosed in the above-mentioned US. Pat. No. 3,423,118. The latch handle 15 is provided with a conventional cylinder lock-equipped pushbutton 16 by means of which the latch of this invention may be actuated through the medium of a spindle 17 that projects from the pushbutton 16 toward the latch casing 5 axially through a transverse opening I8 in the door 1. At the side of the casing 5 disposed toward the stop strip 3, the flange 7 is projected outwardly between the side walls 8 and 9 to provide a barrier portion 19, see particularly FIGS. 3-5.

A rotary latch bolt 20 is formed to provide alatch hook portion 21-, an abutment portion 22 that cooperates with the latch hook portion 2] to define a strike receiving recess 23, a lip 24 on the abutment portion 22, and a pair of ratchet teeth 25 and 26. Further, the latch bolt 20 is formed to provide laterally spaced side walls 27 which define opposite sides of an inwardly opening recess 28. A pivot shaft 29 extends through aligned openings in the side walls 227 transversely of the latch bolt 20, and through other aligned openings in the casing side walls 8 and 9 to journal the latch bolt 20 for rotation in the casing 5 on an axis substantially parallel to the plane of the inner surface of the door 1. As shown in FIGS. 3 and 4, the lip 24 is adapted to engage the barrier portion 19 to limit rotary movement of the latch bolt 20 in a latching direction. A strike 30 is formed to provide an outer curved edge portion 31 that is adapted to be received within the recess 22 of the latch bolt 19, and a mounting flange portion 32 having suitable openings therein for reception of mounting screws shown by dotted lines in FIG. 1 and indicated at 33, whereby the strike 30 is rigidly mounted on the door frame 2. In the embodiment shown, the strike 30 is mounted on the stop strike 3 of the door frame 2.

As shown particularly in FIGS. 3 and 4, the rotary latch bolt 20 is disposed with the latch hook portion 21 engaging the strike 30 and the lip 24 engaging the barrier portion 19 when the door 1 is closed and in engagement with the stop strip 3 of the door frame 2. The latch bolt 20 is yieldingly urged in a direction to move the latch hook portion 21 thereof away from engagement with the strike 30 and angularly inwardly of the casing to its latch released position shown in FIG. 5. The latch bolt is yieldingly urged in this direction of rotation toward its latch released position by a torsion spring 34 encompassing the pivot shaft 29 within the recess 28 and having one arm 35 bearing against a wall of the recess, and another arm 36 extending outwardly of the recess 28 and bearing against a push-plate 37 hereinafter to be more fully described. The rotary latch bolt 20 is held in a latched strike-engaging position and released for rotation imparted thereto by the torsion spring 34 in a direction away from engagement with the strike 30, by means of an actuator 38 comprising a head portion 39 disposed within the casing 5 and a handle portion 40 disposed in laterally spaced generally parallel relationship to the adjacent inner surface 4 of the door 1. The head 39 is formed to provide a transversely reduced lug 41 having a transverse opening or notch 42 therethrough whereby the actuator 38 is pivotally mounted on a shaft 43 that is mounted in its opposite ends in aligned openings in the casing side walls 8 and 9, the axis of the shaft 43 being parallel to that of the shaft 29. The lug 41 is further formed to provide a pawl 44 that is disposed to selectively engage the ratchet teeth and 26 of the rotary latch bolt 20. As shown in FIGS. 3 and 4, the pawl 44 engages the ratchet tooth 25 to hold the latch hook 21 in engagement with the strike and the lip 24 substantially in engagement with the barrier portion 19 against yielding bias of the torsion spring 34. Pivotal movement of the actuator 38 in a direction to withdraw the pawl 44 from engagement with the ratchet tooth 25 will permit the torsion spring 34 to rotate the latch bolt 20 in a direction to move the ratchet tooth 26 toward abutting engagement with the pawl 44. When the ratchet tooth 26 engages the pawl 44, the latch hook 21 will be withdrawn into the casing 5 and laterally away from the strike 30. During spring-imparted rotary movement of the latch bolt 20, the abutment portion 22 thereof engages the extreme outer edge of the curved strike portion 31 and urges the door 1 toward an open position. The handle portion is somewhat wider than the head portion 39, and at its inner end is formed to provide a pair of shoulders 45 that engage the edges of the casing side walls 8 and 9 adjacent the intumed lip 11 to limit pivotal movement of the actuator 38 in a latch bolt engaging direction. Pivotal movement of the actuator 38 in the opposite direction is limited by engagement of the inturned lip 11 with a stop flange portion 46 on the actuator head 39. The actuator 38 is yieldingly urged in a direction of its pivotal movement on the axis of the shaft 43 by a coil compression spring 47 having one end coiled around a retaining button on the actuator head 39, the opposite end of the spring 47 having abutting engagement with a generally triangular retainer plate 49 having opposite ends mounted on a pair of mounting bosses 50 integrally formed with the inner base portion 6 of the casing 5, the extended ends of the bosses 50 being preferably peened to securely hold the retainer plate 49 in place. The retainer plate 49 is formed to provide an outwardly projecting ear 51 to hold the adjacent end of the spring 47 against lateral movement relative to the retainer plate 49.

Means for releasably locking the actuator 38 in engagement of the pawl 44 thereof with the ratchet tooth 25, to hold the rotary latch bolt 20 against strikereleasing rotation, comprises a rotary locking member 52 and a cooperating lever-like rigid link 53 including a relatively long lever arm 54 and a relatively shorter lever arm 55 that terminates in a laterally inwardly projecting lug 56. Intermediate the arms 54 and 55, the link 53 is provided with a transversely projecting boss 57. The link 53 is disposed between the head 39 of the actuator 38 and the adjacent side wall 8 of the casing 5, the boss 57 being joumalled in an opening 58 in the side wall 8, see particularly FIG. 9. As there shown, the lug 56 is disposed within a laterally outwardly opening notch 59 in the head 39, the notch defining a side wall portion 60 against which the lug 56 is adapted to abut, as shown by dotted lines in FIG. 3. In FIG. 4, the link 53 is disposed with the lug 56 in laterally spaced relation to the side wall portion 60, to permit latchreleasing movement to be imparted to the actuator 38.

The locking member 52 is joumalled for limited rotation in a generally cylindrical recess or cavity 61 in the inner or base portion 6 on the axis of the spindle 17, the member 52 having a generally cylindrical axial boss 62 that is joumalled in an opening 63 in the retainer plate 49. Further, the locking member 52 is provided with an axial opening 64 that is preferably non-circular in cross section and which axially slidably receives the extended end portion of the spindle 17. At one side, the locking member 52 defines a radially outwardly opening notch 65 which receives the adjacent end of the lever arm 54, whereby rotary movement of the locking member 52 in opposite directions moves the lug 56 toward and away from engagement with the notch side wall portion 60 of the actuator head 39. Generally opposite the notch 65, the locking member 52 is provided with a radially outwardly projecting arm 66 that terminates in a handle portion 67 projecting laterally outwardly therefrom through an arcuate opening 68 in the base portion 6,

see particularly FIGS. 1 and 2, whereby the locking member 52 may be manually rotated between locked and unlocked positions. The locking member 52 and link 53 are shown in their locked positions in FIGS. 3 and 6, and in their unlocked positions in FIGS. 4, 5 and 7.

The rotary latch bolt 20 is locked against releasing rotation by manually moving the handle 67 to its locking position of FIG. 6, and is normally unlocked for releasing movements from either side of the door by moving the locking member to its unlocked position of FIG. 7. However, should an emergency occur within a building, and an occupant does not think to engage the handie 67 to unlock the latch, the locking member 52 may be rotated to its unlocked position and the latch bolt released for unlatching movement by exerting more than usual unlatching pressure on the handle 40. In this case, pressure of the notch side wall portion 60 against the lug 56 will be sufficient to swing the link 53 in a direction to rotate the locking member 52 to its unlocked position of FIG. 7 while simultaneously releasing the latch bolt 20 for unlatching rotation. For releasably holding the locking member 52 in either its locked or unlocked positions, the pivotal member 52 is provided with a pair of angularly spaced radial notches 69 and 70, each to which is engaged by a detent portion 71 formed in the retainer plate 49. When the locking member 52 is rotated to its locked position, the detent 71 is received in the notch 69, the detent 71 being received in the notch 70 when the locking member 52 is rotated to its unlocked position. It will be appreciated that the retainer plate 49 is made from resilient sheet metal to yieldingly hold the locking member 52 in either of its said'positions.

For the purpose of releasing the latch bolt 20 for unlatching movement from the opposite side, or outside, of the door 1, we provide the push-plate 37 which is preferably stamped or otherwise formed from metal, and which comprises a base portion 72, depending flanges 73 and 74 at opposite ends of the base portion 72, and laterally spaced sidemembers 75 extending outwardly from the base portion in a direction opposite that of the flanges 73 and 74. The side members 75 are pierced to provide axially aligned openings 76 through which extends the shaft 43 to journal the push-plate 37 for pivotal movements within the casing 5. As shown particularly in FIGS. 3-5, the flange 73 provides a base of resistance for the spring arm 36. Further, the free end of the flange 73 is disposed in closely spaced relation to the adjacent surface of the locking member 52, and engages the sarne to limit pivotal movement of the push-plate 37in one direction. The side members 75 have arm portions 77 that are disposed to engage shoulder portions '78 at opposite sides of the actuator head 39, and the base portion 72, adjacent the flange 73, overlies the locking member opening 64 and the adjacent end of the spindle 17. With this arrangement, when the locking member 52 is rotated to its unlocked position, inward movement of the exterior pushbutton 16 will impart locking movement of the push-plate 37 in a direction to move the actuator 38 to disengage the pawl 44 from the ratchet tooth to release the latch bolt 20. it will be noted that, when the locking member 52 is rotatedto its locked position, a surface 79 thereof is disposed in close proximity to the flange 74 of the push-plate 37 to limit pivotal movement of the pushplate 37 ina latch-releasing direction so that, when the locking member 52 is moved to its locked position, the pawl 44 cannot be moved out of engagement with the ratchet tooth 25. Thus, the rotary latch bolt 20 can be released from the exterior of the door, when the lock 52 is in its locked position, only by inserting a key, not shown, into the lock of the pushbutton l6, and rotating the spindle 17 in a direction to move the locking member 52 to its unlocked position.

It should be further noted that, should anyone rotate the latch bolt 20 to its latched position and lock the same therein while the door is open, the door cannot be closed. Thus, a person cannot he accidentally locked out of doors by someone playing with the lock V cation, and that modification may be made without departure from the spirit and scope of the invention, as defined in the claims.

What is claimed is:

1. Door latch mechanism comprising:

a. a casing adapted to be secured to a door hingedly mounted in a door frame;

b. a latch bolt journaled in said! casing for common bodily movements with the door and for rotation between angularly spaced latched and unlatched positions and including a latch hook portion, an abutment portion and a ratchet portion;

c. a stationary strike element adapted to be mounted on the door frame in the path of movement of said latch bolt in common with said door for engagement with said latch bolt hook portion to hold the door against opening movement;

(1. yielding means urging the latch bolt in a direction of rotary movement to disengage said hook portion from said strike element;

e. an actuator including a ratchet engaging pawl, said actuator being mounted in said casingfor limited movements of said pawl relative to said ratchet portion;

f. a yielding element urging said actuator in a direction to move said actuator into engagement of said pawl with said ratchet portion;

g. said abutment portion being positioned to be engaged by said strike, when said latch bolt is in its unlatched position during closing movements of the door, to rotate said latch bolt into its latched position during final closing movement of the door; h. a locking element journaled in said casing for rotation between angularly spaced locked and unlocked positions on an axis transversely of thedoor, when said casing is secured to the door;

i. and a rigid link pivotally mounted in said casing on an axis generally normal to the axis of rotation of said locking element, said link having an end portion engaging said locking element to be pivotally moved responsive to rotation of said locking element, and another portion engaging said actuator to restrain the same against unlatching movement when said locking element is rotated to its locked position.

2. The door latch mechanism defined in claim 1 in which said actuator is pivotally mounted in said casing on an axis parallel to the axis of rotation of said latch bolt and the pivot axis of said link, and normal to the axis of rotation of said locking element, characterized by means including a detent for releasably holding said locking element in said locked position thereof.

3. The door latch mechanism defined in claim 2 in which said locking member defines an axial cross sectionally noncircular opening, characterized by a lock spindle axially slidably fitting at least a portion of said noncircular opening and adapted to extend transversely through said door for connection to operating means on the opposite side of the door, and a pushplate pivotallymounted in said casing on an axis parallel to the axis of rotation of said latch bolt and having a portion operatively engaging and moving said actuasaid push-plate actuator engaging portion comprising a pair of laterally spaced side arms straddling a'portion of said actuator and engageable with shoulders thereon to move said actuator. 

1. Door latch mechanism comprising: a. a casing adapted to be secured to a door hingedly mounted in a door frame; b. a latch bolt journaled in said casing for common bodily movements with the door and for rotation between angularly spaced latched and unlatched positions and including a latch hook portion, an abutment portion and a ratchet portion; c. a stationary strike element adapted to be mounted on the door frame in the path of movement of said latch bolt in common with said door for engagement with said latch bolt hook portion to hold the door against opening movement; d. yielding means urging the latch bolt in a direction of rotary movement to disengage said hook portion from said strike element; e. an actuator including a ratchet engaging pawl, said actuator being mounted in said casing for limited movements of said pawl relative to said ratchet portion; f. a yielding element urging said actuator in a direction to move said actuator into engagement of said pawl with said ratchet portion; g. said abutment portion being positioned to be engaged by said strike, when said latch bolt is in its unlatched position during closing movements of the door, to rotate said latch bolt intO its latched position during final closing movement of the door; h. a locking element journaled in said casing for rotation between angularly spaced locked and unlocked positions on an axis transversely of the door, when said casing is secured to the door; i. and a rigid link pivotally mounted in said casing on an axis generally normal to the axis of rotation of said locking element, said link having an end portion engaging said locking element to be pivotally moved responsive to rotation of said locking element, and another portion engaging said actuator to restrain the same against unlatching movement when said locking element is rotated to its locked position.
 2. The door latch mechanism defined in claim 1 in which said actuator is pivotally mounted in said casing on an axis parallel to the axis of rotation of said latch bolt and the pivot axis of said link, and normal to the axis of rotation of said locking element, characterized by means including a detent for releasably holding said locking element in said locked position thereof.
 3. The door latch mechanism defined in claim 2 in which said locking member defines an axial cross sectionally noncircular opening, characterized by a lock spindle axially slidably fitting at least a portion of said noncircular opening and adapted to extend transversely through said door for connection to operating means on the opposite side of the door, and a push-plate pivotally mounted in said casing on an axis parallel to the axis of rotation of said latch bolt and having a portion operatively engaging and moving said actuator in a direction to release said latch bolt responsive to axial movement of the spindle against the push-plate to pivotally move the same.
 4. The door latch mechanism defined in claim 3 in which said push-plate is pivotally mounted in said casing on the axis of pivotal movement of said actuator, said push-plate actuator engaging portion comprising a pair of laterally spaced side arms straddling a portion of said actuator and engageable with shoulders thereon to move said actuator. 